jspecracer7

Okay, I bought my FD and it always(ALWAYS) backfires. I've put on the cat, and taken off the cat...still backfires. Thought it would be the computer running too rich so I switched mine out with the stock one...still same problem.

Doesn't matter what throttle position I'm in...hot or cold engine...new or old spark plugs...it still backfires...

Also, I've noticed that I go through spark plugs like it's cool...I'm changing them more than normal...like every two to three weeks...and I don't drive my car that much since I don't have a license...

Why the HELL is my car doing this?!?

see my sig for mods...

the_saint

Does it backfire while cruising at a constant speed? or when you shift or lift off the gas?

My car often spits out fire when decelerating in gear for a brief moment, when shifting at high RPM/WOT. This is usually accompanied with a bang

Maybe your injectors are stuck open? I mean perhaps your fuel maps are ok, but you are delivering too much fuel. Changing plugs that often is not normal in my mind. what do the plugs look like? Are you running rich/lean?

the_saint

Mahjik

iTrader: (1)

I don't know about the plugs, but the backfiring probably came from the Downpipe mod. When I replaced my pre-cat with a downpipe, I began to here the backfires as well.

RedFD

I just bought my 93 recently too and it has always backfired. All that is done to it is a catback, and hose job. I always thought it was normal for rotorys to backfire. Is there something wrong with my car? (by the way.... it backfires when you let up on the gas... or let up to switch gears)

mmaragos

Are you guys talking about backfiring or just popping? With what happens on my FD, I would call popping (maybe slight backfiring is a better way to say it - as people like to say, "Damn, I just popped my engine."). Not the traditional piston engine KABOOM. More like pop, pop, pop, pop...when I left of the gas.

Popping/slight backfiring for a modded rotary is normal. Backfiring (depending on your definition) may or may not be normal. Severe backfiring is not normal.

If you are changing your spark plugs frequently (2-3 weeks = how many miles for you? - for me that would be in the hundreds of miles), then something is definitely not right. I would think that you should be getting at least 8,000 to 12,000 miles off good plugs. I would start by checking out the fuel delivery and the ignition system too.

skunks

I just got mines about a month ago and it backfires all the time. I have a straight pipe and occationally blow flames as well. i dont really mind although it scares me when it does a loud backfire cuz i always think that I just blew the engine. you could buy a fuel computer like the superafc from apexi and turn down the fuel that way but personnaly, id rather run a little more rich then a little more lean!!! also, how come you are going thru spark plugs so fast, you are using only ngk or stock replacement type right??? anything else is a no no.

Im pretty sure your gonna have to accept it though cuz thats just was rotary engines do when you are running with out a dp and cat. also just a heads up but you might wanna check your boost if you dont have a boostgauge, running without a dp and cat will make you overboost like crazy!

wonder1and

In my case this bang, pop, whatever was eliminated by the PFC. I always had quite a loud bang whenever I shifted etc. (almost knocked a guy off a street bike) The flame is caused by unburned fuel... you going through spark plugs like girl friends is a bad thing. Like what was said before you might want to check your inj. or switch'em out for bigger ones. FYI when you blow your engine your idle will start to suck and also if it goes while your accelerating you car will lurch and then you can say SH*T. anyway good luck
Ryker

jspecracer7

My car backfires when I decelerate, but throttle position doesn't matter(WOT or cruising). I get the normal pop, pop, pop which is okay, but sometimes I get the KA-BOOM!...when I decelerate.

I put the cat's back on and that didn't help, so I'm guessing that I need to buy a PFC.

I might put maybe 100 miles in a three week period(maybe 150 miles if i'm lucky), so I don't know why the plugs wear out so quickly. They look normal(carboned up, and no white marks on the tip...and the tip's not rounded out).

I know that I'm running higher boost because of the front pipe/mid pipe and the computer was tuned for that.

I always run stock plugs since rotary's go thru plugs fairly quickly(but in my case too quickly).

This is my official third rotary so I'm VERY familiar with what a blown engine looks like, what type of plugs need to go in, etc....

Do any of you think it could be a bad TPS or a stuck open fuel injector?

sometimes the trailing plugs come out wet(they smell like fuel). I've checked the trailing plug wires and I'm getting spark so it's not that or the coils.

Thanks Guys!

jspecracer7

Also, my exhaust temp never gets over 9...well at 3rd gear at 7000 rpm's my exhaust temp gets to 9.2, but never over...She run REALLY sweet. HELP PLEASE!!!

Pressurized

I would like to say that it's normal, because that's how my car is. In fact my last set of plug lasted about 700miles, and I don't drive it too hard. But those were also the stock spec plugs instead of the platinum's which did last a lot longer.

I get the typical pop, pop, pop while decelerating and I get the the louder pop when shifting at high RPM's....but then every once in a while I'll get the true 'backfire' that sounds like a cherry bomb in an aluminum trash can, but this only seems to happen around the 3k RPM range.

What kinda gas do you run? I've noticed since I use the 100 octane racing gas, my car doesn't pop as much...

I'm not sure what causes this, if you find out let me know, I think I'm in the same boat as you...

jspecracer7

well I'm running 89 octane gas...didn't even think that could be causing the KA-BOOM sound coming from the exhaust...

How long did your platinum's last?

I was thinking of going to those since they do last longer, but now much longer...

jarinhawaii

oh my gosh, dont you know not to use anything under 92 or 93!!! in any case i dont think the 89 octane is causing back fire it just that you should be using higher octane due to the boost.

jspecracer7

Yes I know that the "Owners Manual" says to use nothing less than 92 octane....

However, I'm in a car club with 4 FD's...three of them running approximately 500 hp....on 89 octane gas

One of them has koki FC rotors/eccentric shaft/counter balance and so his compression is a little lower than stock FD rotors...

The other two are running fine with about 50 knock on PFC...

And then there's mine....

So riddle me this....why can their cars handle 89 octane with "only" 500 hp, but my whopping "300" (estimated) won't handle anything less than 92 octane?

mmaragos

Well, if you can confirm that nothing is wrong with your fuel injection or ignition system or other...then I would guess that the difference in the above is tuning. They are running PFCs and you are running an RE CPU. The PFC did wonders for my car as far as idling, acceleration, etc., but I don't have any experience with the RE CPU. Maybe it is the root cause of your backfiring.

I would try running 92-93 octane and see what happens. I would also switch over to platinum plugs. But you may have to dig deeper (fuel system, ignition, CPU?).

I think that the platinum plugs will last significantly longer. How much for your situation? I don't know. Because maybe you have an ignition issue that is shortening the life of your plugs. But you should get in the neighborhood of 10,000 miles on the plugs.

Pressurized

Yeah..my platinums lasted about 9000miles, they probably would've gone longer but I fouled them out with leaded racing gas. As for maybe being an ignition problem, that might be a culprit, I know I just changed my wires and o2 sensor and I get less popping.

jspecracer7

I changed my exhaust from the Greddy to a JIC bullet(available only in Japan) and it slowed the backfiring up...I only backfire at high rpm's now and every now and again when I'm cruising...thanks GOD

I'll be getting a pfc here shortly...with a t-04s boosting 1.3, I should be happy